> On 04 May 2015, at 19:59 , franknarf <by.hook...@gmail.com> wrote: > > But I'm still wondering why diag() uses c()...? With it being so slow, I'd > be inclined to write a qdiag() without the c() and just use that the next > time I need matrix algebra. Any insight would be appreciated; thanks!
Well, there are two possibilities: Either it is deliberate or it isn't. The latter isn't too unlikely, given that the effect is seen for large matrices. I would appear to be a matter of O(n) (picking out n items) vs. O(n^2) (copying an n x n matrix), but this might drown out in a context involving matrix multiplication and/or inversion, both of which are O(n^3). If it is deliberate, the question is why. There could be devils in the details; notice in particular that c() strips off non-name attributes. However, I'm not aware of a situation where such attributes could cause trouble. -pd -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
